The present invention relates to a drive unit for a hoist, an elevator in particular, with a motor, a transmission, a braking means and a housing.
Such drive unit is known from EP 706 968. The drive unit known in this publication is of simple construction and has a short over-all length and generates low mass forces. The motor and the transmission can in cantilever manner be flanged to the brake housing serving as stator and thus being the only component requiring fixation on the foundation or socle. This solution proved to be successful, however, a further constructional simplification such that in case of compact, and possibly extremely compact, structure installation periods during assembly of the drive unit and/or insertion of the drive unit into an elevator are caused is desirable. The invention intends to solve this problem.
The invention achieves this aim by arranging a drive to support a brake body and a transmission drive shaft, by having a housing for a motor and the brake body arranged together, and by supporting the drive shaft exclusively at a wall which extends between the motor and the brake body. A drive unit is created which is superior to the generic prior art in that the motor as well as the braking unit (preferably including the support of the continuous drive shaft) together are arranged in the housing of the drive unit.
This is just not the case in EP 0 706 968, since there the motor together with its housing is flanged to a separate brake housing which also serves as stator for the entire drive unit. The invention takes another way, since it "saves" one of the housings and instead integrates the brake and motor thereof in one single construction. The particular advantage of this construction results from the simplification of assembly of the drive unit in the plant and in the reduced space required in an elevator. In case of retrofitting the space available for insertion often is very confined. When a worm gear pair has to be substituted for, a planetary gear has to fit in axial direction of the drive wheel, i.e. has to be aligned at 90.degree. to the existing transmission.
In accordance with a preferred embodiment of the present invention, the construction is further simplified and shortened in that in the housing at least one (preferably essential) part of the transmission (planetary or cyclo or spur gear) is arranged as mounted transmission or as built-in transmission so that the housing in this part also forms the transmission housing. A separate transmission housing thus can be done without in this area (preferably only a housing cover is provided for still).
A further particularly preferred modification of the present invention further integrates brake and ventilator and/or rotor sleeve to form one unit. In this solution the housing can be constructed in the manner described above or in conventional construction. Brake and ventilator can be combined in particularly simple manner in that in the manner of a drum or disk ventilator blades are formed to the brake body. Optionally or alternatively furthermore a (pot-shaped) rotor sleeve is arranged on the brake drum (e.g. formed thereto).
By transferring the ventilator blades to the "outside" it is possible that the stator winding essentially protrudes into the interior of the brake drum for in this way reducing the constructional length. The unification of brake drum and rotor sleeve to form one cast part/shaped part results in a reduction of treatment and mounting costs and in a shortening of the drive shaft. In some sizes of construction even the support bearing at the shaft end can be done without, this contributing to a further reduction of costs and constructional length.
Further preferred embodiments of the invention result from that a continuous shaft forms the motor shaft as well as the transmission shaft and that the brake body is fixed within the brake housing on the shaft.
It turned out to be particularly advantageous to use a permanent magnet motor with rotor and stator, which (as compared to the remaining dimensions of the drive unit) is built in flat construction and is located "opposite" to the brake drum (realizable in infinitely variable manner) on the shaft. Therein e.g. the rotor of the permanent magnet motor is arranged on the (pot-shaped) outer wall of the brake drum and the stator is arranged on the inside wall of the housing. Thus, the brake drum serves as simultaneous carrier sleeve for the rotor, this opening the possibility of reducing the total diameter and the axial height of the drive. This e.g. is advantageous for applications in which the "constructional length" of the drive unit is less critical. Above all a high torque can be realized in case of small rotor diameter.
In another manner of realization of a permanent magnet drive an extremely narrow motor (disk motor) is arranged on a correspondingly enlarged diameter opposite to the brake drum on the elongated cast body.
Summarizing, the new housing construction results in a clear reduction of mounting time and in a constructional simplification followed by saving material and a reduction of constructional size (e.g. by doing without elements like shaft screwing, end bearing of the drive shaft and ventilator unit).
In the following the invention will be explained in more detail with reference to preferred embodiments.